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Posted: November 8, 2007

Implantable microfluidic device could detect cancer markers

(Nanowerk News) A tiny implant now being developed at the Massachusetts Institute of Technology (MIT) could one day help doctors rapidly monitor the growth of tumors and the progress of chemotherapy in cancer patients. The implant, developed by Michael Cima, Ph.D., and Robert Langer, Ph.D., both investigators at the MIT-Harvard Center of Cancer Nanotechnology Excellence, contains nanoparticles that can be designed to test for different substances, including cancer markers and metabolites such as glucose and oxygen, which are associated with tumor growth. The device can also track the effects of cancer drugs: Once inside a patient, the implant could reveal how much of a certain cancer drug has reached the tumor, helping doctors determine whether a treatment is working in a particular patient.

Although such nanoparticles have been used before, this study, which was published in the journal Lab on a Chip ("Multi-reservoir device for detecting a soluble cancer biomarker"), demonstrates that encasing the nanoparticles in a silicone delivery device would allow them to remain in patients’ bodies for an extended period of time. The device can be implanted directly into a tumor, allowing researchers to get a more direct look at what is happening in the tumor over time.

The new technique, known as implanted magnetic sensing, makes use of detection nanoparticles composed of dextran-coated iron oxide. Antibodies specific to a target molecule—in this case, the investigators used antibodies that recognize the soluble cancer biomarker human chorionic gonadotrophin-β—are attached to the surface of the particles. When the target molecules are present, they bind to the particles and cause them to clump together. That clumping can be detected by magnetic resonance imaging.

The nanoparticles are trapped inside the silicone device, which is sealed off by a porous membrane. The membrane allows molecules smaller than 10 nm to get in, but the detection particles are too big to get out. The device can be engineered to test for many different biomarkers simultaneously and to monitor the presence of chemotherapy drugs. In addition, the device could also be used to check whether a tumor is growing or shrinking, or whether it has spread to other locations, by sensing the amount and location of tumor markers.